The present invention relates to a method of correcting various structural errors of a SCARA robot which may be produced in machining parts thereof, assembling the parts and/or installing a SCARA robot and, particularly, to a structural error correction method for a SCARA robot suitable to position arms thereof in a numerically . instructed position with a high absolute accuracy.
A conventional error correction method for a SCARA robot is disclosed in N. Furuya et al., "Correction of Parameters of SCARA Robot by Teaching", Seimitsu-Kikai, vol. 49, No. 9, (September 1983), pages 1223 to 1228, in which a correction is made by obtaining a length of a robot arm and a mounting angle thereof by measuring three points on a straight line or four points constituting a four-cornered area by touching by a finger of the robot arm.
In the conventional method mentioned above, in order to obtain structural errors of a robot, two different coordinates values are necessary, namely, a coordinates value in an absolute coordinate system having an origin in a certain position after installing the robot and also a coordinates value in the robot coordinate system having an origin at a position in which the robot is installed. However, it is very difficult to perform positional measurements on such an absolute coordinate system.